Graft vasculopathy of vascularized composite allografts in humans: a literature review and retrospective study

Urinary bladder transplantation in humans - current status and future perspectives

Urinary bladder vascularized allograft transplantation in humans is currently extensively being investigated worldwide, owing to the theoretical potential of this approach as a therapeutic option for individuals with end-stage, non-oncological bladder conditions or congenital bladder pathologies. To date, a successful attempt at urinary bladder autotransplantation was carried out in a heart-beating brain-dead research human donor. The robot-assisted surgical technique was shown to be optimal for performing this procedure, achieving a good performance in terms of both bladder allograft collection as well as vascular, ureterovesical and vesicourethral anastomoses. The urinary bladder vascularized allograft would be an alternative to traditional urinary diversion methods that rely on the use of intestinal segments, potentially avoiding adverse effects associated with these approaches. However, different from ileal urinary diversion, bladder transplantation would require lifelong immune suppression. Clinical trials are in progress to assess the vascularized bladder allograft transplantation technique, as well as the safety of this procedure in oncological and non-oncological indications.

An Update on the Survival of the First 50 Face Transplants Worldwide

Importance

Since 2005, a total of 50 face transplants have been reported from 18 centers in 11 countries. The overall survival of the grafts has not yet been established.

Objective

To assess the survival of the face transplant grafts and evaluate factors potentially influencing it.

Design, Setting, and Participants

Data on all the transplants included in this multicenter cohort study were collected at participating transplant centers for updated nonpublished data, supplemented with literature review for nonparticipating centers. Data from 2005 until September 2023, were included. Data were analyzed from November 11, 2005, through September 18, 2023. Patients included the first 50 patients in the world to have received a face transplant.

Exposure

Face transplant graft.

Main Outcomes and Measures

The primary outcome was the overall survival of the face transplant graft, defined as either transplant loss or patient death. The secondary outcome was the number of acute rejection episodes per year.

Results

The 50 transplants were performed on 39 men (81%) and 9 women (19%) with a median age of 35 (range, 19-68) years at the time of the transplant. The median follow-up time was 8.9 (range, 0.2-16.7) years. During the follow-up, 6 transplants were lost with 2 patients retransplanted. There were 10 patients who died, 2 of whom had lost a transplant. The 5- and 10-year survival of the transplants was 85% (SD, 5%) and 74% (SD, 7%), respectively. The sequential number of the transplant in the world was a significant predictor of survival (hazard ratio, 95; 95% CI, 90-100; P < 05). The median number of acute rejection episodes per year was 1.2 (range, 0-5.3) for the transplants that were lost and 0.7 (range, 0-4.6) for the transplants that survived. No correlation with patient and transplant variables was detected for either the transplant survival or the number of rejection episodes.

Conclusions and Relevance

In this study, the overall survival of the face transplants is encouraging. These data suggest that the acceptable long-term survival of face transplants makes them a reconstructive option for extensive facial defects.

18 years of face transplantation: Adverse outcomes and challenges

BACKGROUND

Since the first procedure performed in 2005, face transplantation has been debated as viable approach for the treatment of severe craniofacial defects. Despite the benefits provided, the experience in face allotransplantation has brought to light a significant risk of complications, including allograft removal or loss, and mortality. The present study is intended to provide an updated review on complications and major challenges witnessed over 18 years of experience in the field.

METHODS

A systematic review of PubMed, MEDLINE, Cochrane, Google, and Google Scholar databases on face transplantation was conducted according to PRISMA guidelines up to April 2023. Articles providing details on cases of face allograft loss, removal, and patient death were included. Online articles and media reports were assessed to include information not disclosed in peer-reviewed literature. Face transplant centers were contacted to have updated follow-up information on single-face transplant cases.

RESULTS

The search yielded 1006 reports, of which 28 were included. On a total of 48 procedures performed in 46 patients, adverse outcomes were gleaned in 14 cases (29%), including seven allograft losses (14.6%), and the death of ten patients (21.7%). Chronic rejection was the leading cause of allograft loss, with a median time from transplant to irreversible rejection of 90 months (IQR 88.5-102). The main causes of death were infectious complications, followed by malignancies, non-compliance to immunosuppression, and suicide. The median time to death was 48.5 months (IQR 19-122).

CONCLUSIONS

To the best of our knowledge, this is the first study providing a comprehensive review of adverse outcomes in face transplantation. Considering the high rate of major complications, the heterogeneity of cases and single-center approaches, and the absence of published standards of care, the development of a consensus by face transplant teams holds the key to the field's advancement.

Defining chronic rejection in vascularized composite allografts - do we have reliable surrogates to look for?

PURPOSE OF REVIEW

Chronic rejection (CR) is a major threat in the field of vascularized composite tissue allografts (VCAs) as it causes graft dysfunction and usually graft loss. Unfortunately, knowledge of CR in VCA is incomplete because of the limited number of VCA recipients, the heterogeneous nature of VCAs and the short follow-up.

RECENT FINDINGS

The diagnosis of CR in VCA has relied on clinical and pathological findings. Clinical changes include graft fibrosis, dyschromia and ischemic/necrotic ulcerations. Pathological changes primarily affect allograft vessels and manifest with graft vasculopathy (i.e. myo-intimal proliferation and luminal narrowing of allograft vessels, leading to graft ischemia). Attempts are made to diagnose CR with non- or minimally-invasive techniques, such as imaging studies (ultrasound biomicroscopy, functional magnetic resonance imaging) and serum biomarkers. These techniques provide interesting results and further insight into the mechanisms of CR in VCA.

SUMMARY

The diagnosis of CR in VCA still relies mainly on clinicopathological graft alterations; unfortunately, these become overt rather late during the rejection process, when reversal of CR is problematic. More recent, minimally- or non-invasive techniques have provided encouraging results, but their usefulness in the diagnosis of CR requires further studies. These data highlight the paramount importance of CR prevention.

Novel cell-based strategies for immunomodulation in vascularized composite allotransplantation

PURPOSE OF REVIEW

Vascularized composite allotransplantation (VCA) has become a clinical reality in the past two decades. However, its routine clinical applications are limited by the risk of acute rejection, and the side effects of the lifelong immunosuppression. Therefore, there is a need for new protocols to induce tolerance and extend VCA survival. Cell- based therapies have emerged as an attractive strategy for tolerance induction in VCA. This manuscript reviews the current strategies and applications of cell-based therapies for tolerance induction in VCA.

RECENT FINDINGS

Cellular therapies, including the application of bone marrow cells (BMC), mesenchymal stem cells (MSC), adipose stem cells, regulatory T cells (Treg) cells, dendritic cells and donor recipient chimeric cells (DRCC) show promising potential as a strategy to induce tolerance in VCA. Ongoing basic science research aims to provide insights into the mechanisms of action, homing, functional specialization and standardization of these cellular therapies. Additionally, translational preclinical and clinical studies are underway, showing encouraging outcomes.

SUMMARY

Cellular therapies hold great potential and are supported by preclinical studies and clinical trials demonstrating safety and efficacy. However, further research is needed to develop novel cell-based immunosuppressive protocol for VCA.

Moderate LMWH Anticoagulation Improves Success Rate of Hind Limb Allotransplantation in Mice

Background

The mouse hind limb model represents a powerful research tool in vascularized composite tissue allotransplantation, but its applicability is limited due to poor graft survival (62%-83%). Vascular thrombosis and massive hemorrhage are the major causes for these drop-outs. We hypothesize that because of better anticoagulation effect and lower risk of thrombocytopenia, application of low molecular weight heparin (LMWH) will minimize vascular complications and enhance graft and animal survival.

Methods

Fifty allogeneic hind limb transplantations were performed (C57BL/6 to DBA/2 mice) using five different anticoagulation protocols. Bleeding and thromboembolic events were recorded macroscopically by postoperative hemorrhage and livid discoloration of the graft, respectively. Graft perfusion and survival were monitored daily by capillary-refill-time of graft toes within 2-3 seconds. Vascular congestion and tissue necrosis were examined by histological evaluation of hematoxylin-eosin-stained tissue sections.

Results

All transplantations were technically successful. Increase in thromboembolic events and a concomitant decrease in bleeding events were observed with the decreasing concentration of heparin in the perfusion solution. Although treatment of donor and recipient with low dose of LMWH could not reduce thromboembolic events, moderate dose effectively reduced these events. Compared with the poor outcome of graft perfusion with heparin alone, additional treatment of donor and recipient with low dose of LMWH improved graft and animal survival by 18%. Interestingly, animals treated with moderate dose of LMWH demonstrated 100% graft and animal survival.

Conclusions

Treatment of donor and recipient mice with a moderate dose of LMWH prevents vascular complications and improves the outcome of murine hind limb transplants.

Genetic modification of limbs using ex vivo machine perfusion

Genetic engineering is a promising tool to repair genetic disorders, improve graft function or to reduce immune responses towards the allografts. Ex vivo organ perfusion systems have the potential to mitigate ischemic-reperfusion injury, prolong preservation time or even rescue organ function. We aim to combine both technologies to develop a modular platform allowing the genetic modification of vascularized composite (VC) allografts. Rat hind limbs were perfused ex vivo under subnormothermic conditions with lentiviral vectors. Specific perfusion conditions such as controlled pressure, temperature and flow rates were optimized to support the genetic modification of the limbs. Genetic modification was detected in vascular, muscular and dermal limb tissues. Remarkably, skin follicular and interfollicular keratinocytes as well as endothelial cells (ECs) showed stable transgene expression. Furthermore, levels of injury markers such as lactate, myoglobin and lactate dehydrogenase (LDH) as well as histological analyses showed that ex vivo limb perfusion with lentiviral vectors did not cause tissue damage and limb cytokine secretion signatures were not significantly affected. The use of ex vivo VC perfusion in combination with lentiviral vectors allows an efficient and stable genetic modification of limbs representing a robust platform to genetically engineer limbs towards increasing graft survival after transplantation.

Face transplantation: A longitudinal histological study focusing on chronic active and mucosal rejection in a series with long-term follow-up

The 2007 Banff working classification of skin-containing Tissue Allograft Pathology addressed only acute T cell-mediated rejection in skin. We report the longitudinal long-term histological follow-up of six face transplant recipients, focusing on chronic and mucosal rejection. We identified three patterns suggestive of chronic rejection (lichen planus-like, vitiligo-like and scleroderma-like). Four patients presented lichen planus-like and vitiligo-like chronic rejection at 52 ± 17 months posttransplant with severe concomitant acute T cell-mediated rejection. After lichen planus-like rejection, two patients developed scleroderma-like alterations. Graft vasculopathy with C4d deposits and de novo DSA led to subsequent graft loss in one patient. Chronic active rejection was frequent and similar patterns were noted in mucosae. Concordance between 124 paired skin and mucosal biopsies acute rejection grades was low (κ = 0.2, p = .005) but most grade 0/I mucosal rejections were associated with grade 0/I skin rejections. We defined discordant (grade≥II mucosal rejection and grade 0/I skin rejection) (n = 55 [70%]) and concordant (grade≥II rejection in both biopsies) groups. Mucosal biopsies of the discordant group displayed lower intra-epithelial GranzymeB/FoxP3 ratios suggesting a less aggressive phenotype (p = .08). The grading system for acute rejection in mucosa may require phenotyping. Whether discordant infiltrates reflect a latent allo-immune reaction leading to chronic rejection remains an open question.

Facial Trauma 8 years after a Face Transplantation

Over the past 20 years, vascularized composite allografts (VCAs) have emerged as a realistic option in reconstructive surgery. Long-term follow-up reports indicate that face transplant patients have gained in quality of life and social integration. However, they require close monitoring of their immunosuppressive therapy because they are at high-risk for acute rejection episodes, leading eventually to chronic rejection and allograft loss. Reported acute rejection episodes in VCA recipients occur due to low immunosuppressive therapy (mainly due to lack of patient compliance or decreased doses of immunosuppressants to counter side-effects). Repeated mechanical traumas have recently been shown to trigger acute rejection episodes, especially in hand transplant patients. This article reports our experience of a 10-year follow-up of a 57-year-old face transplant patient and the management of his accidental facial trauma. To our knowledge, our patient is the first to undergo a major trauma on his VCA endangering his graft function and vitality. This report discusses the management of an acute surgical situation in those particular patients, and the challenges that arise to avoid acute rejection of the allograft. Ten years into his face transplant and at 18 months follow-up after his facial trauma, our patient shows great aesthetic and functional outcomes and remains rejection-free; a very encouraging result for all VCA candidates.

Abdominal Wall Transplantation: Indications and Outcomes

Purpose of Review

This article aims to review published outcomes associated with full-thickness vascularized abdominal wall transplantation, with particular emphasis on advances in the field in the last 3 years.

Recent Findings

Forty-six full-thickness vascularized abdominal wall transplants have been performed in 44 patients worldwide. Approximately 35% of abdominal wall transplant recipients will experience at least one episode of acute rejection in the first year after transplant, compared with rejection rates of 87.8% and 72.7% for hand and face transplant respectively. Recent evidence suggests that combining a skin containing abdominal wall transplant with an intestinal transplant does not appear to increase sensitization or de novo donor-specific antibody formation.

Summary

Published data suggests that abdominal wall transplantation is an effective safe solution to achieve primary closure of the abdomen after intestinal or multivisceral transplant. However, better data is needed to confirm observations made and to determine long-term outcomes, requiring standardized data collection and reporting and collaboration between the small number of active transplant centres around the world.

Vascularised composite allotransplantation in solid organ transplant recipients: A systematic review

INTRODUCTION

A solid organ transplant (SOT) recipient, already taking immunosuppression, may represent the ideal candidate for vascularised composite allograft transplantation (VCA). However, concerns have been raised about the potential risk of SOT loss or the need for increased immunosuppression to sustain the VCA. This systematic review examines all published cases of SOT recipients who have received a VCA to establish associated morbidity and immunosuppression requirements.

METHODS

A systematic review was performed in accordance with the PRISMA guidelines. The PubMed, MEDLINE and EMBASE databases were searched for original articles published between January 1997 and May 2019. Only articles relating to patients who had received both a VCA and SOT with a reported follow up of greater than six months were included.

RESULTS

Fifteen articles were identified, including data from 39 VCAs in 37 patients. There was no increase in the number of SOT rejection episodes, complications such as post-transplant lymphoproliferative disorder or graft versus host disease, de novo donor specific HLA antibodies or short-term risks to the recipient when compared with SOT in isolation. One child required a sustained increase in their baseline immunosuppression following bilateral hand transplantation.

CONCLUSIONS

In this small heterogeneous cohort, the addition of a VCA to a SOT does not appear to increase the short-term risks to the SOT or the patient with comparable results to SOT in isolation. However, data are often poorly reported and longer-term follow up and uniform reporting of outcomes would be beneficial to more accurately assess the safety profile of combining VCA with SOT.

Costimulation Blockade in Vascularized Composite Allotransplantation

Vascular composite allotransplantation (VCA) is a field under research and has emerged as an alternative option for the repair of severe disfiguring defects that result from infections or traumatic amputation in a selected group of patients. VCA is performed in centers with appropriate expertise, experience and adequate resources to effectively manage the complexity and complications of this treatment. Lifelong immunosuppressive therapy, immunosuppression associated complications, and the effects of the host immune response in the graft are major concerns in VCA. VCA is considered a quality of life transplant and the risk-benefit ratio is dissimilar to life saving transplants. Belatacept seems a promising drug that prolongs patient and graft survival in kidney transplantation and it could also be an alternative approach to VCA immunosuppression. In this review, we are summarizing current literature about the role of costimulation blockade, with a focus on belatacept in VCA.

Defining chronic rejection in vascularized composite allotransplantation-The American Society of Reconstructive Transplantation and International Society of Vascularized Composite Allotransplantation chronic rejection working group: 2018 American Society of Reconstructive Transplantation meeting report and white paper Research goals in defining chronic rejection in vascularized composite allotransplantation

Objectives:

This report summarizes a collaborative effort between the American Society of Reconstructive Transplantation and the International Society of Vascularized Composite Allotransplantation to establish what is known about chronic rejection in recipients of vascularized composite allografts, with an emphasis on upper extremity and face transplants. As a picture of chronic rejection in hand and face vascularized composite allografts emerges, the results will be applied to other types of vascularized composite allografts, such as uterine transplantation.

Methods:

The overall goal is to develop a definition of chronic rejection in vascularized composite allografts so that we can establish longitudinal correlates of factors such as acute rejection, immunosuppressive therapy, de novo donor-specific antibody and trauma/infection and other external factors on the development of chronic rejection. As Dr Kanitakis eloquently stated at the 2017 International Society of Vascularized Composite Allotransplantation meeting in Salzburg, “Before we can correlate causative factors of chronic rejection, we have to define what chronic rejection in VCA is.”

Results:

The first meeting report was presented at the sixth Biennial meeting of the American Society of Reconstructive Transplantation in November 2018. Based on collaborative efforts and descriptions of clinical cases of chronic rejection in vascularized composite allograft recipients, a working definition of chronic rejection in vascularized composite allografts with respect to overt functional decline, subclinical functional decline, histologic evidence without functional decline, and normal allograft function in the absence of histologic evidence of chronic rejection is proposed.

Conclusions:

It is the intent of this collaborative working group that these working definitions will help to focus ongoing research to define the incidence, risk factors and treatment regimens that will identify mechanisms of chronic rejection in vascularized composite allografts. As with all good research, our initial efforts have generated more questions than answers. We hope that this is the first of many updates.

A chronic rejection model and potential biomarkers for vascularized composite allotransplantation

BACKGROUND

Chronic rejection remains the Achilles heel in vascularized composite allotransplantation. Animal models to specifically study chronic rejection in vascularized composite allotransplantation do not exist so far. However, there are established rat models to study chronic rejection in solid organ transplantation such as allogeneic transplantation between the rat strains Lewis and Fischer344. Thus, we initiated this study to investigate the applicability of hindlimb transplantation between these strains to imitate chronic rejection in vascularized composite allotransplantation and identify potential markers.

METHODS

Allogeneic hindlimb transplantation were performed between Lewis (recipient) and Fischer344 (donor) rats with either constant immunosuppression or a high dose immunosuppressive bolus only in case of acute skin rejections. Histology, immunohistochemistry, microarray and qPCR analysis were used to detect changes in skin and muscle at postoperative day 100.

RESULTS

We were able to demonstrate significant intimal proliferation, infiltration of CD68 and CD4 positive cells, up-regulation of inflammatory cytokines and initiation of muscular fibrosis in the chronic rejection group. Microarray analysis and subsequent qPCR identified CXC ligands 9-11 as potential markers of chronic rejection.

CONCLUSIONS

The Fischer344 to Lewis hindlimb transplantation model may represent a new option to study chronic rejection in vascularized composite allotransplantation in an experimental setting. CXC ligands 9-11 deserve further research to investigate their role as chronic rejection markers.

Importance of the Major Histocompatibility Complex (Swine Leukocyte Antigen) in Swine Health and Biomedical Research

In pigs, the major histocompatibility complex (MHC), or swine leukocyte antigen (SLA) complex, maps to Sus scrofa chromosome 7. It consists of three regions, the class I and class III regions mapping to 7p1.1 and the class II region mapping to 7q1.1. The swine MHC is divided by the centromere, which is unique among mammals studied to date. The SLA complexspans between 2.4 and 2.7 Mb, depending on haplotype, and encodes approximately 150 loci, with at least 120 genes predicted to be functional. Here we update the whole SLA complex based on the Sscrofa11.1 build and annotate the organization for all recognized SLA genes and their allelic sequences. We present SLA nomenclature and typing methods and discuss the expression of SLA proteins, as well as their role in antigen presentation and immune, disease, and vaccine responses. Finally, we explore the role of SLA genes in transplantation and xenotransplantation and their importance in swine biomedical models.

Upper extremity and craniofacial vascularized composite allotransplantation: ethics and immunosuppression

Vascularized composite allotransplantation (VCA) is the name most often used to refer to the transplantation of anatomical units composed of multiple tissue types (skin, bone, muscle, tendon, nerves, vessels, etc.) when such transplants do not have the primary purpose of extending life, as is the case in the more familiar field of solid organ transplantation (SOT). A serious interest in VCA developed in the late twentieth century following advances in immunosuppression which had led to significant improvements in short and medium-term survival among SOT recipients. Several ethical concerns have been raised about VCA, with many being connected in one way or another to the limitations, burdens, and risks associated with immunosuppression. This article will focus on upper extremity and craniofacial VCA, beginning with a brief review of the history of VCA including reported outcomes, followed by a discussion of the range of ethical concerns, before exploring in greater detail how immunological issues inform and shape several of the ethical concerns.